In the coupon book that comes with the seasons pass, there is a coupon for "bring a friend for $20 off" during Fright Fest, but you'd need to be WITH the season passholder to use that I think. I'd offer you my coupon, but I don't think I'd be able to go that day. If you live near or visit other Six Flags parks, you might as well just get a 2013 season pass, which should get you in for the rest of the 2012 season too.
They usually have all of the coasters open during Fright Fest, as far as I recall. There are extra charges for some of the special Fright Fest attractions - haunted houses, etc.

Prices differ depending on which day you go on, but you can get them for about $40 for Fright Fest. And, like glutton said, coasters are open during that time, though the fright fest attractions cost extra. Hope this helps!

Six Flags offers the lowest prices generally through their web site. The web site offers match the best local market offers (i.e. fast food, soda cans). The exception is the friend coupons offered to passholders.